Estimating how long someone may live is very difficult. It’s usually discussed in terms of ranges; that is, hours to days, days to weeks, or weeks to months. It’s important to realize that every situation is different, that many factors are involved, and that everyone responds differently.

Fluid intake has the biggest effect on immediate survival. Our bodies tend to have several weeks worth of reserve energy from food stores, but lack of fluid causes problems with kidney function within a few days. When someone is no longer taking in any fluid, and if he or she is bedridden (and so needs little fluid) then this person may live as little as a few days or as long as a couple of weeks.

In the normal dying process people lose their sense of hunger or thirst. In addition, they may not be alert enough to swallow safely. This is a sign that body systems are starting to shut down. Death may be days or hours away. The patient may feel more comfortable if the mouth is moistened, but this is to relieve a dry mouth, not to satisfy thirst.

When a decision is made to discontinue life-sustaining treatments such as artificial feeding or intravenous fluids, then a patient’s remaining time depends on how sick he or she is at that point, and whether there are complications such as pneumonia. Commonly, even after intravenous fluids are stopped the patient may take sips of fluids, ice chips, or swabs to moisten the mouth. This may provide more fluid than people realize, and it may extend survival time. All these unique health factors affect how someone experiences the total burden of the illness and how long she or he will live. Some people believe that a person's will to live also affects a person's burden of illness and so may also affect life expectancy.

Families and health care providers may be uncomfortable when someone refuses artificial food and fluids, as this seems like basic nurturing. Yet, legally and ethically artificial nutrition and hydration is considered health care treatment, just like surgery, dialysis or other medical interventions. People have the right to decline medical treatments, and others must respect this decision.

There is no way to predict when someone’s condition may change suddenly. Therefore, it’s important to address any issues that need attention before the patient becomes too weak to do so. Things that need to be done or said should happen sooner rather than later.